Where does Sophocles accomplish catharsis in Oedipus Rex?

The catharsis is in the ending or resolution to the drama. It is here where the "cleansing" of both audience and protagonist is present. When Act IV is concluded, both Oedipus and the audience are both horrified at the news of the shepherd. It is at this moment, where much in way of filth has reached its zenith. Oedipus' pride, his boasting of free will, and his absolute confidence that he can overcome the power...

The catharsis is in the ending or resolution to the drama. It is here where the "cleansing" of both audience and protagonist is present. When Act IV is concluded, both Oedipus and the audience are both horrified at the news of the shepherd. It is at this moment, where much in way of filth has reached its zenith. Oedipus' pride, his boasting of free will, and his absolute confidence that he can overcome the power of divined fate are illusions whose collision presens itself at the end of Act IV, and whose shards open Act V. Jocasta's suicide, at "being married to her son and thus had given birth to his children," adds to the horrific filth that presents itself to the audience. The catharsis begins when Oedipus blinds himself. This allows him a chance to gain the same type of "sight" that Tieriesias, whom he treated with scorn and disdain, possessed. Yet, Sophocles is wise enough to know that catharsis, or the act of purification has to happen on both political and personal levels for this drama to meet the standard for the saga was only personal, but political regarding a king and his obligation to his subjects. It is for this reason that Oedipus asks to face his subjects, blinded and humiliated. As a broken man, one who seeks to make right what he unknowingly made wrong, Oedipus asks for political forgiveness. However, where the true catharsis lies is not his how he wishes it for himself, but rather for his children. It is here where we begin to see purity and a sense of reclamation evident, catharsis becoming formed before our very eyes. Oedipus' own pride has become secondary to the hopes for his children. It is here where redemption and restoration happens simultaneously for Oedipus and for the audience, who are reminded that their own sins have to be seen in their larger context of an individual's life with the closing words of the chorus.